(reuters) -- The comments were the latest in a series of tough remarks from Iran's leadership, showing a united front between its reformist and conservative factions as U.S. President Donald Trump prepares to harden policy towards Tehran this week.
"In the closed session Zarif emphasised that if the Americans take any steps against the nuclear deal that the Islamic Republic of Iran will give them a more crushing response," Shahbaz Hassanpour, a lawmaker representing the city of Sirjan, told the Islamic Republic News Agency (IRNA).
Another lawmaker, Behrouz Nemati, said the foreign minister discussed specific steps Trump and the U.S. Congress might take, and Iran's plans for reciprocal action to each anticipated U.S. move. Nemati did not say what actions Zarif had described.
Trump is expected this week to "decertify" the landmark 2015 deal under which Iran agreed with global powers to accept curbs on its nuclear programme in return for the lifting of international sanctions.
Decertification would not by itself withdraw the United States from the agreement, but would pass that decision on to Congress, requiring lawmakers to decide within 60 days whether to re-impose sanctions.
Trump is also expected to declare Iran's Revolutionary Guards Corps a terrorist organisation.
Washington has already blacklisted other entities and individuals for supporting Guards' activities, but has not blacklisted the Guards themselves.
The threat of increased U.S. pressure has been met by a united front of criticism from within Iran, with members of the pragmatic faction that seeks greater interaction with the West showing their support for the Guards.
Iranian newspapers ran photos on Tuesday of Zarif, the urbane, U.S.-educated foreign minister, laughing and hugging the head of the Guards, Mohammad Ali Jafari.
During the meeting with Zarif, parliament members expressed their support for the Guards, Hassanpour said. Zarif also noted during the session that European countries will continue backing the nuclear deal regardless of what actions the U.S may take, Hassanpour told IRNA.